use EPOS-based boundary-helper throughout

src/mol-gl/renderable/util.ts

src/mol-gl/scene.ts

src/mol-math/geometry/boundary-helper.ts

src/mol-math/geometry/epos-helper.ts

src/mol-math/geometry/lookup3d/grid.ts

src/mol-math/geometry/primitives/box3d.ts

src/mol-math/geometry/primitives/sphere3d.ts

src/mol-model/loci.ts

src/mol-model/structure/structure/element/loci.ts

src/mol-model/structure/structure/util/boundary.ts

src/mol-plugin-state/manager/structure/selection.ts

src/mol-repr/structure/visual/label-text.ts